feat(menu): add menu item focus styles

[bmdalex]

Menu

This PR main purposes:

• adds keyboard focus styles by leveraging existing functionality;
• updates existing styles to adhere better to Teams theme;

TODO

• Conformance test
• Minimal doc site example
• Stardust base theme
• Teams Light theme
• Teams Dark theme
• Teams Contrast theme
• Confirm RTL usage
• W3 accessibility check
• Stardust accessibility check
• Update glossary props table
• Update the CHANGELOG.md

Description

type="primary"

All primary (type="primary") menus get updated background for active, focus and hover states.

underlined

Underlined menus get new styles for active, focus and hover states.

iconOnly

Menus with only icons as item get new styles for active, focus and hover states.

1. regular:

2. inverted (by tweeking variables):

3. vertical (with vertical prop):

[codecov]

Codecov Report

Merging #286 into master will decrease coverage by 0.28%.
The diff coverage is 68.75%.

@@            Coverage Diff             @@
##           master     #286      +/-   ##
==========================================
- Coverage    89.9%   89.62%   -0.29%     
==========================================
  Files          62       62              
  Lines        1159     1166       +7     
  Branches      150      173      +23     
==========================================
+ Hits         1042     1045       +3     
- Misses        115      119       +4     
  Partials        2        2

Impacted Files	Coverage Δ
src/components/RadioGroup/RadioGroupItem.tsx	100% <100%> (ø)	⬆️
src/components/Button/Button.tsx	95.74% <100%> (ø)	⬆️
src/components/Menu/MenuItem.tsx	80% <61.53%> (-8.89%)	⬇️
src/index.ts	100% <0%> (ø)	⬆️

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[bmdalex]

ready for review:
@miroslavstastny @mnajdova @levithomason @kuzhelov

[miroslavstastny]

Code looks good, not sure about removing focus ring for all Menu types.

[mnajdova]

Left one comment for consideration, other then that, looks good by me. Please create an issue for the isFromKeyboard service explaining the problem you encountered.